Field of the Present Invention
The field of the present invention is aircraft safety investigation in conjunction with vehicle navigation and relative location.
Background Concerning the Need and Use of the Current Invention
Aircraft lost over water are often extremely difficult to locate. Location is important because data and voice information recorded on the vehicle and physical evidence from the wrecked vehicle are essential to investigation of the cause of the loss. Larger aircraft are currently required to carry acoustic pingers attached to their recording devices that are intended to allow searchers to locate not only the recording device but the lost aircraft itself. Because of the vast spaces in large bodies of water such as oceans, the initial discovery of even the approximate location is the crucial step. The search can take a long time and the power source of the pinger is subject to exhaustion before this step is accomplished. Because of limitations concerning space, weight and power conservation the range of pinger devices is limited. This limitation is a major factor in the difficulty of location.
The current invention is directed to a solution of this difficulty. Because a searcher can use substantial and renewable power resources, it is possible to broadcast a signal from the searcher to the pinger device with much greater ease and at a much greater range than from the pinger to the searcher. Even before the searcher has made any discovery that the pinger is in its neighborhood, the pinger can be enabled to modify the ping signal on the basis of information gained from the receipt of the broadcast interrogation signal. Doing this in a way that increases the ability of the searcher to discover the hard to find ping signal is a solution to this difficult location problem and the principle subject of the current invention.
This is distinct from just making a more effective pinger, because it works in the phase of the search where one way communication only is established and uses that communication to facilitate discovery. There are many ways the ping signal can be modified for this purpose. Some of them are described in the embodiments disclosed. The most salient ones include timing the ping to arrive at a time predictable by the searcher, beaming the ping in the direction from which the interrogation signal arrived and implementing the ping with parameters requested by the searcher. This last method is important because the searcher with its greater resources may know its own best modes of search and have current information about the search environment. If information based on that is broadcast and received by the pinger device, then the ping can be adapted with the benefit of information available to either the searcher or the pinger.
There are many kinds of information that can be taken from the interrogation signal for the purpose of determining the best mode of transmitting pings. First, there is the fact of receipt of the interrogation signal itself, distinct from any information about the nature of the signal. This can initiate pinging or wake up portions of the pinger device. This is primarily a way of conserving power to enable a more robust energy budget for powerful pinging and for extending the life of the power source. Second, the ping device can measure parameters of the incoming interrogation signal such as the intensity and the direction of arrival. This has many uses in determining the best mode of pinging. Third, the search device can encode and embed information in the interrogation signal. This can carry useful information about the location of the searcher, time of transmission of the interrogation signal, ping characteristics requested by the searcher, the current search environment and other things known to the searcher.
Existing systems using transceiver technology often have interactive methods of facilitating communication, but they do not use the ability to broadcast into a large space in an effort to locate a difficult to detect responder having the ability to tailor its response on the basis of the interrogation. They, especially, do not use this technology as the basis of an extended long term search for an object requiring a large number of interrogations from different locations to have a significant chance of being located.
Prior Patents to be Distinguished from the Current Inventive Concept
US Patent Application 2013-0070556 to Huskamp discloses a system for reflecting acoustic signals directed to a sunken aircraft. It contemplates passive reflectors with specific frequency characteristics to allow identification of the reflected signals without use of power allowing unlimited life. If differs from the current invention in not having a signal receiver and a signal transmitter and in not modifying the return signal.
U.S. Pat. No. 5,582,566 (A) to Imasaka concerns a transponder which returns a signal with a fixed delay. The delay is used to provide an offset to the distance measurement for a device using the transponder. This invention is not concerned with lost or submerged objects and does not vary the return signal.
U.S. Pat. No. 6,469,654 (B1) to Winner concerns a transponder landing system and discusses a protocol for increasing the accuracy of tracking the transponder. It discusses a “Dual Diversity Antenna System” in the background section wherein a transponder with two antennas returns a signal using only the antenna which receives the stronger interrogation signal. This differs from the current invention in that it is not concerned with lost or submerged objects as herein defined. The purpose is to maintain continuous and reliable communication during maneuvers of the aircraft. The selection of the antenna for response is not a variation of a parameter of the ping signal as herein defined; because the antenna selection is not done to vary the signal in any way, but is done specifically to maintain an unvarying signal despite changes in the attitude of the aircraft.
U.S. Pat. No. 7,646,330 (B2) to Karr concerns a two way communication system where the remote transponder makes its return signal coherent with the interrogation signal. It describes a wake-up process to periodically listen for interrogations, which is distinct for a low power listening mode. The purpose of this system is to provide reliable two way communication of identification codes and other information with very low power use by the remote device and not to provide initial discovery of the remote device by the interrogating device. It is not concerned with lost or submerged objects as herein defined.
U.S. Pat. No. 8,624,774 (B2) to De Rosa concerns a device to locate an associated device. It uses a low power listening receiver to wake up the device on receipt of an interrogation. It is not concerned with lost or submerged objects as herein defined. The patent is directed to a method of measuring the relative locations of the device and making this information available to the search device.
The differences described above between the current inventive concept and the patents cited are only illustrative and there are many other distinctions in each case.
Prior Patent for Reference
The patent in this section is referenced to provide clarity to the use of various technologies used in the embodiments described herein and to provide further enablement in the implementation of those embodiments.
The patent listed in this section is incorporated herein by reference in its entirety. Furthermore, where a definition or use of a term in a reference, which is incorporated by reference herein, is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
U.S. Pat. No. 4,613,864 (A) to Hofgen describes the use of one way ranging from multiple locations to calculate the relative location of a user device from the signals of multiple satellites. This is the basic technology of GPS systems. The technology is here used in an embodiment to calculate the relative location of a target device to a moving search device on the basis of the receipt of multiple interrogation signals.